The aim of this thesis was two-fold: first, to evaluate four different functional aspects of the speech and language spectrum; oral-motor function, voice, /s/-articulation and phonology in preschool children with tonsillar hypertrophy before and after surgical treatment. The second aim was to investigate weather the outcome of surgery was equal for two surgical techniques; tonsillectomy or tonsillotomy combined with adenoidectomy when necessary. In all included publications (I-IV), 67 children on waiting list for tonsil surgery and randomized to either tonsillectomy (33) or tonsillotomy (34) participated. The children were assessed and audio-recorded within a month before surgery and six months postoperatively. Results were compared to age-matched control groups.

In the first study, oral motor function was assessed using the Nordic Orofacial Test-Screening, NOT-S, consisting of a structured interview and a clinical examination. Before surgery, the children in the study group differed in all domains of the structured interview in comparison to age-matched controls and in the clinical examination regarding the parameters deviant lip position and trouble nose-breathing. Postoperatively oral motor functions were normalized in both surgical groups and no differences to age matched controls were observed. In study two, recordings of three sustained vowels (/α , u, i/) and 14 words elicited by picture naming were analysed both perceptually and acoustically. Compared to the controls, significant differences were found in the study group preoperatively with higher ratings on Visual Analogue Scales (VAS) for the voice quality parameters “hyponasality” and “compressed/throaty” and also lower for pitch. Significantly higher values on all studied perturbation measures (jitter, shimmer and Noise to Harmonics Ratio) were found. Regarding center frequencies of formants, the study groups had lower F3 values for /u / and also lower F2 and F3 for / i / compared to age-matched controls. After surgery there were no significant differences between the perceptual ratings of voice quality of the two surgical groups and there were no significant differences between the children in the surgical groups and the corresponding controls. The acoustic analyses showed a decrease in all the measures of perturbation for the study group after surgery with a slight difference between the two surgical groups. The children in the tonsillotomy group had higher shimmer value for /u/ and higher NHR for /α/. In comparison to the older controls significantly higher values were found an all perturbation measures and the difference seen regarding formant frequencies for the /i/-sound in comparison to controls still remained. The significantly lower third formant (F3) of the /u/-sound also remained. When comparing pre- versus postoperative results for the surgical group as a whole, a decrease was found on all perturbation measures postoperatively, however the differences were not statistically significant. A significant increase was found in formant 3 for /α/ and /u/ was found.

The material used in the third study were speech samples containing the /s/-sound and elicited by picture naming and sentence repetition. Before surgery the study group was rated to have more indistinct /s/-sounds than agematched controls. The acoustic analyses showed that the study group had lower spectral peak values for the /s/-sound than controls. After surgery the operated children’s /s/-production did not differ perceptually from the older controls, neither as a whole group nor when divided according to surgical methods. Regarding the acoustic analyses however, the study groups differed from the age-matched control group showing that noise duration was longer and the peak location higher in the study groups.

In study four, a Swedish phonology test was performed and transcribed phonetically. The transcription of each child was analyzed in terms of phonological processes and categorized into one of six developmental stages according to the model developed by Nettelbladt (1983) and adapted by Sahlén, Reuterskiold-Wagner, Nettelbladt & Radeborg (1999). A majority of the children in the study group (62.7 %) showed a slowed phonological development preoperatively (developmental stages 0-4), compared to the age-matched control group. Postoperatively the children in both surgical groups had improved their phonological skills. However, they were still behind in comparison to age-matched controls and the difference was even larger than before surgery.

The results of this thesis project have clinical relevance for both speech and language pathologists (SLP’s) and ear-nose and throat-surgeons (ENT-surgeons). SLP’s must be aware of the potential impact of tonsillar hypertrophy on oral-motor function and the speech and language spectrum to be able to help affected children adequately and ENT- surgeons should include oral motor and speech and language problems as additional indications for tonsillar surgery.